Various processes have been proposed for producing dimethyl ether from natural gas. One such process involves co-feeding natural gas with an enriched oxygen stream to an autothermal reformer to produce syngas. Dimethyl ether may then be produced in a two stage process. In a first stage, methanol is synthesized from the syngas. In the methanol synthesis step, un-reacted gas from the methanol synthesis reactor may be recycled back to the reactor, thereby acting as a syngas quench cooler. The recycle ratio (recycle gas to syngas feed gas) can be quite high in commercial practice, such as from 3:1 to 7:1, due to equilibrium limitations in methanol conversion. In the second stage, methanol is fed to a dimethyl ether reactor where dimethyl ether and water are produced. Water is separated from dimethyl ether is a subsequent stage.
Air separation (for providing an enriched oxygen feed), autothermal reforming, and substantial internal product recycle imposes significant operating and equipment costs for conventional systems for producing dimethyl ether from natural gas. It would therefore be desirable to provide new integrated processes for the production of dimethyl ether from natural gas.